I all, I've never used a window cleaner but I think the time has come.... roughly what do they cost and how often do you get them done? I'm in a country cottage so no road muck but I e got some new big windows letting light in and boy can I see the grime! So three questions - is it worth it, how often do you have them done and roughly how much to expect to pay? We have 15 windows including 2 doors and 2 skylights. Thanks.